1 + 2 + 3 + 4 + ------ + 18 = কত?

1 + 2 + 3 + 4 + ------ + 18 = কত?

A 168

B 171

C 174

D 176

Solution

Correct Answer: Option B

1+2+3+4+.............+18=?

সমষ্টি = n(n+1)/2 [এখানে n=18]
=9×19
=171